An apparatus includes a deformable mirror. The deformable mirror includes a reflective surface configured to reflect a high-energy laser (HEL) beam and to focus the HEL beam on a target. The deformable mirror also includes multiple actuators configured to adjust a shape of the reflective surface in order to maintain focus of the HEL beam on the target over a specified range of distances between the deformable mirror and the target. At least one portion of the reflective surface is configured to be adjusted by the actuators and obtain convex, flat, and concave shapes.